#include<stdio.h>
int getScore(char g)
{
    int a;
    if(g == 'A') a = 95;
    if(g == 'B') a = 85;
    if(g == 'C') a = 75;
    if(g == 'D') a = 65;
    if(g == 'E') a = 40;
    return a;

}
int main()
{
    char ch;
    double sum = 0, n = 0;
    while(scanf("%c", &ch), ch != '\n')
    {
        sum += getScore(ch);
        n ++;
    }
    printf("%.1f", sum*1.0 / n);
    return 0;
}